Western equine encephalitis virus
Encyclopedia
The Western equine encephalomyelitis virus is the causative agent of relatively uncommon viral disease Western equine encephalomyelitis (WEE). An Alphavirus
of the family Togaviridae
, the WEE virus is an arbovirus
(arthropod-borne virus) transmitted by mosquitoes of the genera Culex
and Culiseta
. WEE is a recombinant virus
between two other closely related yet distinct encephalitis
viruses. There have been under 700 confirmed cases in the U.S. since 1964.
In the U.S. WEE is seen primarily in states west of the Mississippi River
. The disease is also seen in countries of South America
. WEE is commonly a subclinical infection; symptomatic infections are uncommon. However, the disease can cause serious sequelae in infants and children. Unlike Eastern equine encephalitis, the overall mortality of WEE is low (approximately 4%) and is associated mostly with infection in the elderly. There is no vaccine for WEE and there are no licensed therapeutic drugs in the U.S. for this infection.
Alphavirus
In biology and immunology, an alphavirus belongs to the group IV Togaviridae family of viruses, according to the system of classification based on viral genome composition introduced by David Baltimore in 1971. Alphaviruses, like all other group IV viruses have a positive sense single stranded RNA...
of the family Togaviridae
Togaviridae
The Togaviridae are a family of viruses, including the following genera:* Genus Alphavirus; type species: Sindbis virus, Eastern equine encephalitis virus, Western equine encephalitis virus, Venezuelan equine encephalitis virus, Ross River virus, O'nyong'nyong virus, Chikungunya* Genus Rubivirus;...
, the WEE virus is an arbovirus
Arbovirus
Arbovirus is a term used to refer to a group of viruses that are transmitted by arthropod vectors. The word arbovirus is an acronym . Some arboviruses are able to cause emergent disease.-Transmission:...
(arthropod-borne virus) transmitted by mosquitoes of the genera Culex
Culex
Culex is a genus of mosquito, and is important in that several species serve as vectors of important diseases, such as West Nile virus, filariasis, Japanese encephalitis, St. Louis encephalitis and avian malaria....
and Culiseta
Culiseta
Culiseta is a genus of mosquitoes. Most Culiseta are cold-adapted species which only occur in warmer climates during the colder parts of the year or at higher elevations where temperatures are low...
. WEE is a recombinant virus
Recombinant virus
A recombinant virus is a virus produced by recombining pieces of DNA using recombinant DNA technology. This may be used to produce viral vaccines or gene therapy vectors....
between two other closely related yet distinct encephalitis
Encephalitis
Encephalitis is an acute inflammation of the brain. Encephalitis with meningitis is known as meningoencephalitis. Symptoms include headache, fever, confusion, drowsiness, and fatigue...
viruses. There have been under 700 confirmed cases in the U.S. since 1964.
In the U.S. WEE is seen primarily in states west of the Mississippi River
Mississippi River
The Mississippi River is the largest river system in North America. Flowing entirely in the United States, this river rises in western Minnesota and meanders slowly southwards for to the Mississippi River Delta at the Gulf of Mexico. With its many tributaries, the Mississippi's watershed drains...
. The disease is also seen in countries of South America
South America
South America is a continent situated in the Western Hemisphere, mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere. The continent is also considered a subcontinent of the Americas. It is bordered on the west by the Pacific Ocean and on the north and east...
. WEE is commonly a subclinical infection; symptomatic infections are uncommon. However, the disease can cause serious sequelae in infants and children. Unlike Eastern equine encephalitis, the overall mortality of WEE is low (approximately 4%) and is associated mostly with infection in the elderly. There is no vaccine for WEE and there are no licensed therapeutic drugs in the U.S. for this infection.